O2 says iPhone strained London network as China sales top 300K

U.S.-based AT&T isn't the only wireless carrier to see its network come under heavy strain due to the popularity of the iPhone. Meanwhile, Apple's official provider for the handset in China this week reportedly reached the 300,000 unit sales mark.

Following suspicions Monday that AT&T may have made a desperate attempt to ease congestion on its overcrowded 3G network by halting online sales of the iPhone to New York City residents, Reuters reports that UK-based O2 has been battling similar issues overseas for the past six months.

Facing an 18-fold increase in traffic from bandwidth-guzzling smartphones like the iPhone, O2s London network reportedly crashed under the pressure numerous times since the summer, leaving some customers with no way to make calls or transmit data for periods of time.

O2 says an investment of $48 million in its network above the capital city eased the problems by December and included the deployment of 200 extra mobile stations.

"Where we haven't met our own high standards then there's no question, we apologize to customers for that fact," Chief Executive Ronan Dunne told the Financial Times. "But it would be wrong to say O2 has failed its customers en masse."

Meanwhile, official iPhone sales in China are reportedly gaining steam after a slow start left some onlookers concerned that Apple wouldn't be able to gain traction in the region saturated with grey market devices.

Apple's exclusive provider in the area, China Unicom, is believed to have sold its 300,000th unit on Monday, marking an acceleration in sales of the touch-screen handset since the carrier announced that it passed the 100,000 mark just 20 days ago. By comparison, it took China Unicom 40 days to sell its first 100,000 units.

China remains a vast opportunity for the iPhone with its more than 700 million wireless subscribers. Still, Apple's faced its share of difficulties cracking the market due to counterfeit iPhones that sell for considerably less, and a government mandate that prompted the company to cripple its official offering by restricting Wi-Fi capabilities.